Esta tese apresenta um estudo original das propriedades estruturais e eletrônicas dos nanotubos de carbono de parede simples (NTCPS) por meio de complexos de titânio e a possibilidade de adsorção e redução do cromo hexavalente Cr (VI) utilizando a teoria da densidade funcional. Cr (VI) é um dos principais poluentes ambientais, sua remoção apresenta várias dificuldades, e resulta em poluição ambiental, causando problemas de saúde. A adsorção de Cr (VI) foi investigada a partir das moléculas de cromato e dicromato no semicondutor NTCPS funcionalizado com complexos de TiO2, TiO4H4 e Ti2O6H4. Os resultados sugerem que os NTCPS funcionalizados são grandes candidatos à adsorção de Cr (VI). Além disso, as estruturas de banda eletrônica mudaram na região próxima à energia de Fermi das bandas de valência e de condução para os NTCPS pristino e funcionalizados com sistemas de cromo. Após adsorção de Cr (VI) nos sistemas, observa-se a formação de moléculas com menor toxicidade e atividade carcinogênica o que não ocorreu sem a presença dos nanotubos. / This thesis presents an original study of the structural and electronic properties of doped single-walled carbon nanotubes (SWCNT) through titanium complexes and the possibility of adsorption and reduction of hexavalent chromium Cr(VI) using density functional theory. Cr(VI) is one of the major environment pollutants, its removal presents several difficulties, and it results in industrial pollution, causing health problems. The adsorption of Cr(VI) was investigated from the chromate and dichromate molecules in semiconductor SWCNT functionalized with TiO2, TiO4H4 and Ti2O6H4 complexes. The results suggest that the functionalized SWCNT are great candidates to adsorb Cr(VI). In addition, the electronic band structures changed in the region near the Fermi energy of the valence and conduction bands for the pristine and functionalized SWCNT with chromium systems. After adsorption of Cr(VI) in the systems, the formation of molecules with less toxicity and carcinogenic activity is observed, which did not occur without the presence of the nanotubes.nanotubes.

Esta tese apresenta um estudo original das propriedades estruturais e eletrônicas dos nanotubos de carbono de parede simples (NTCPS) por meio de complexos de titânio e a possibilidade de adsorção e redução do cromo hexavalente Cr (VI) utilizando a teoria da densidade funcional. Cr (VI) é um dos principais poluentes ambientais, sua remoção apresenta várias dificuldades, e resulta em poluição ambiental, causando problemas de saúde. A adsorção de Cr (VI) foi investigada a partir das moléculas de cromato e dicromato no semicondutor NTCPS funcionalizado com complexos de TiO2, TiO4H4 e Ti2O6H4. Os resultados sugerem que os NTCPS funcionalizados são grandes candidatos à adsorção de Cr (VI). Além disso, as estruturas de banda eletrônica mudaram na região próxima à energia de Fermi das bandas de valência e de condução para os NTCPS pristino e funcionalizados com sistemas de cromo. Após adsorção de Cr (VI) nos sistemas, observa-se a formação de moléculas com menor toxicidade e atividade carcinogênica o que não ocorreu sem a presença dos nanotubos. / This thesis presents an original study of the structural and electronic properties of doped single-walled carbon nanotubes (SWCNT) through titanium complexes and the possibility of adsorption and reduction of hexavalent chromium Cr(VI) using density functional theory. Cr(VI) is one of the major environment pollutants, its removal presents several difficulties, and it results in industrial pollution, causing health problems. The adsorption of Cr(VI) was investigated from the chromate and dichromate molecules in semiconductor SWCNT functionalized with TiO2, TiO4H4 and Ti2O6H4 complexes. The results suggest that the functionalized SWCNT are great candidates to adsorb Cr(VI). In addition, the electronic band structures changed in the region near the Fermi energy of the valence and conduction bands for the pristine and functionalized SWCNT with chromium systems. After adsorption of Cr(VI) in the systems, the formation of molecules with less toxicity and carcinogenic activity is observed, which did not occur without the presence of the nanotubes.nanotubes.

Esta tese apresenta um estudo original das propriedades estruturais e eletrônicas dos nanotubos de carbono de parede simples (NTCPS) por meio de complexos de titânio e a possibilidade de adsorção e redução do cromo hexavalente Cr (VI) utilizando a teoria da densidade funcional. Cr (VI) é um dos principais poluentes ambientais, sua remoção apresenta várias dificuldades, e resulta em poluição ambiental, causando problemas de saúde. A adsorção de Cr (VI) foi investigada a partir das moléculas de cromato e dicromato no semicondutor NTCPS funcionalizado com complexos de TiO2, TiO4H4 e Ti2O6H4. Os resultados sugerem que os NTCPS funcionalizados são grandes candidatos à adsorção de Cr (VI). Além disso, as estruturas de banda eletrônica mudaram na região próxima à energia de Fermi das bandas de valência e de condução para os NTCPS pristino e funcionalizados com sistemas de cromo. Após adsorção de Cr (VI) nos sistemas, observa-se a formação de moléculas com menor toxicidade e atividade carcinogênica o que não ocorreu sem a presença dos nanotubos. / This thesis presents an original study of the structural and electronic properties of doped single-walled carbon nanotubes (SWCNT) through titanium complexes and the possibility of adsorption and reduction of hexavalent chromium Cr(VI) using density functional theory. Cr(VI) is one of the major environment pollutants, its removal presents several difficulties, and it results in industrial pollution, causing health problems. The adsorption of Cr(VI) was investigated from the chromate and dichromate molecules in semiconductor SWCNT functionalized with TiO2, TiO4H4 and Ti2O6H4 complexes. The results suggest that the functionalized SWCNT are great candidates to adsorb Cr(VI). In addition, the electronic band structures changed in the region near the Fermi energy of the valence and conduction bands for the pristine and functionalized SWCNT with chromium systems. After adsorption of Cr(VI) in the systems, the formation of molecules with less toxicity and carcinogenic activity is observed, which did not occur without the presence of the nanotubes.nanotubes.

Une série de complexes à base de titane porteurs de ligands aminodiols de différentes configuration (mélange de diastéréoisomère, meso, racémique ou chiral) ont été synthétisés et caractérisés par différentes techniques spectroscopiques. Ces complexes ont ensuite été utilisés comme amorceurs pour la polymérisation par ouverture de cycles de différents monomères hétérocycliques (L/rac-lactide, caprolactone, butyrolactone et triméthylène carbonate) via un mécanisme de coordination-insertion. Tous les complexes se sont révélés efficaces pour la polymérisation des lactides que ce soit en solution à 70°C ou en masse à 130°C avec un bon contrôle. Lors de la polymérisation du rac-lactide, le complexe porteur du ligand racémique a permis d‟obtenir un polylactide partiellement heterotactique, alors que tous les autres complexes n‟ont conduit qu‟à des polymères atactiques. Tous les complexes se sont également révélés très actifs pour la polymérisation de la caprolactone aussi bien en solution qu‟en masse à 70°C avec un bon contrôle. Des études cinétiques réalisées en solution ont permis de mettre en évidence un ordre cinétique unitaire en monomère. De bonnes activités ont également été obtenues pour la polymérisation de la butyrolactone et du triméthylène carbonate. De plus, le bon contrôle de ce type de la polymérisation a permis de synthétiser des copolymères à blocs du L/rac-lactide et de caprolactone. Enfin, la copolymérisation aléatoire de ces 2 monomères a permis de mettre en évidence une réactivité inversée par rapport aux réactions d'homopolymérisation. / A series of titanium isopropoxides complexes coordinated by enantiopure, racemic, meso and diastereomeric aminodiol ligands have been prepared and characterized by spectroscopic techniques. The complexes were tested as initiators for the ring opening polymerization (ROP) of cyclic esters such as L/rac-lactide, caprolactone, butyrolactone and trimethylene carbonate via coordination-insertion mechanism. In lactide polymerizations, all complexes showed significant activity both in solution at 70°C and in bulk at 130°C with a good control. The complex derived from rac-aminodiol ligand gave partially heterotactic polylactide in ROP of rac-lactide, whereas all other complexes yielded atactic polylactides. For caprolactone polymerizations, all complexes were found to be effective initiators under both solution and bulk conditions (up to 60% monomer conversion was reached within 10 min in bulk condition at 70°C), again with good control. Kinetic studies of ROP of lactides and caprolactone in solution conditions have been investigated and showed a first kinetic order in monomer. Significant activities were also observed for (ROP) of butyrolactone and trimethylene carbonate. Block copolymers of caprolactone and lactides were successfully synthesized with these catalytic systems by sequential polymerization techniques. The complexes were also tested as initiators for the production of random copolymers containing caprolactone and lactides and a reverse order of reactivity was observed between lactide and caprolactone compared to homopolymerization.

This diploma thesis is focused on the design and synthesis of new half-sandwich titanium complexes for anchoring to selected supports (SiO2, SBA-15) and the study of their catalytic activity and selectivity in ethylene trimerization to 1-hexene. The synthetic strategy of half-sandwich titanium complexes with a suitable leaving group for direct anchoring through Ti−O bond was carried out (Cl, Oi-Pr). In addition, the titanium complexes with pendant alkenyl group were prepared and utilised for anchoring to a SiMe2H modified support by Pt-catalysed hydrosilylation reaction. Prepared compounds were characterised by standard spectroscopic methods (IR, NMR, MS). The heterogeneous systems were characterised by MAS NMR and IR spectroscopy, powder XRD, ICP-OES, TGA and the textural parameters were determined from nitrogen adsorption/desorption isotherms. For all prepared materials was studied the catalytic activity for ethylene trimerization and the selectivity to 1-hexene.